Dual pivot toggle mechanism for lock-



Feb- 28, 1956 E. A. voN sr-:GGERN 2,736,221

DUAL PIVOT TOGGLE MECHANISM FOR LOCKING AND RELEASING PIVOTED JAW WRENCHFiled June 14, 1954 'lll/IIIA ll//ll//IJVI/l M W v IN V EN TOR.

En NzsrAyo/v .S2-665m United States Patent DUAL .PIVGT TOGGLE MECHANISMTFOR LOCK- ING RELEASING'P-IVOTED JAW WRENCH This-.invention relates tokpliers of the self-lockingtype,

4and'in'particular to pliers which vhave a release mecha- .nismbywhichthey may be readily unlocked.

z'It is an object of the invention to provide a simple means by whichself-locking pliers, when locked onto an object, .may be releasedtherefromwith a minimum force, :which is1much less .than that requiredto initially lock the pliers.

Another object is to provide a release mechanism which doesnotinvolve-the useof auxiliary levers or triggers #to raffectreleaseibututilizes only the basic plier components.

-A -further Aobject is to provide a release mechanism which is`simple-and does not readily deteriorate or -get out of order.

iFig. lisa plan view of one illustrative embodiment vof the pliers .whenin the open, unlocked position;

Fig. 2 is a sectional view of the release mechanism taken alongthe line.2-2 of Fig. l;

Fig. 3 is afsectional -view-of.the adjustable .toggle joint takenalongthe line 3-3 of Fig. l;

Fig. 4is a plan view-of the pliers of Fig. `1 shown'in the ;closed andlocked position; rand Fig. 5 .is a planview of the pliers-of Fig. .l`shown when `the locking pressure on the plier'jaws has been released,but the jaws have not yet opened.

In the conventional self-locking pliers an over-center rtoggle vjoint-isemployed to hold the pliers closed when llocked on an object. The force-required to release the toggle joint'is equal to that required to closethe toggle.

In thepresent invention, two toggle `joints are arranged inseries, onebeing used for locking the pliers in the lconventional manner, and one,Vhaving a diiferent leverage ratio,"being used to unlock lthe pliers.

The pliers'have a main body -11 towhichy is rigidly fixed a yjaw `12,and a threaded adjusting screw 13 is mounted on the-opposite end. Amovablejaw 14'is lpivoted at the pinpoint 15in body v11 and said jaw hasan operating handle "16 pivotally attached thereto at lpoint 17. Thehandle 16`has arelease link 18 located within and under 4said-handle asshown in the'sectional -view of Fig.' 2, and Vis.pivotallyjoinedftheretoat point 419. A toggle "link'20 vispivotally joined atApoint 21 torelease link 18 and is heldin pivotal engagement with screw 13-'atthe-point 22.

In order to .maintain engagement lat point 22, acpair` of raisedyikno'bs'23 (-Fig. 3) are kformed into the end of link 20 which retainsaid link insidethe semi-circular section 124 of fthe :body 11. "Thissemi-circular section extends for alengthealong the body 11 'atleastAequal to the length --of the V-adjusting screw v13.

Togglelink 20 :is located within and under the irelease link 18-as-shown in the sectional view of Fig. 2 andhas two stops 25 and 26which engage the release link in its closed yand-open positionsrespectively. Release link 18 also has a stop "27 which engages thehandle 16 when in the semi1releasedposition of Fig. 5.

A spring 28 is hooked around thejpivot pin 19 and a hook29in the mainbody 11, and holds the jaws 212 and ,14 in an .openvposition when thepliers arein released position (Fig. 1). It also holds handle 16 inclosed relation to` (in engagement with) link-.18 and'holdstoggle link.20. in engagement with adjustingscrew 13.

2,736,221 patented Feb. 2s, 1956 ice LOperation of thepliers whenclosing on an object 30 is entirely-conventional. Inthe open position(Fig. l) the opening of the jaws is limited by stop 26 in engagementwith vlink 18, which limits the separation of handle v16 from body 1'1,and also by the adjusting screw 13 which regulates the jaw 'openingindependently of that -caused by thehandle motion. Screw 13 is adjustedso that when handle 16-is squeezed down as shown in Fig. 4, the object30 is ffirmly gripped in jaws 12 and 14 in the usual manner. In v'thisposition'saidvgjaws are locked `because toggle joint -pivot '21`liesover-center with respect to toggle joints 17 vand 2.2 as shown by dashedline 31 (Fig. 4). The amount of over-center travel is limited by stop 25whose engagement with'link v118 also limits the motion of handle .16.

In thev closing'andlocking operation as shown by Figs. 1 and 4, the'link'18 remains inside handle l16 and performs no function. -Pivot joint 19lies below joints 17 and21ass'hown by line 31 (Fig. 4) which makes itover center also and .acts as a stiff joint. The amount of over-centertravel is limited by the engagement of tail 32 of link 18 with the underside of handle 16.

To release the, pliers from object'30'pressure is `applied to the-under'side of handle 16 as indicated by arrow 33. yThis Acauses handle16'to separate and move away from release'link 18 as -shown in Fig. 5,leaving links 18 and Y20 engaged to vact"toge'ther, in effect, as asingle stifflink. It is seen that a line 34 (Fig. 5) drawn between,pivot points -19 and 22 passesabove pivot point 21, which puts it`in anover-center relation and maintains stop 25 in engagementwith link 18.The upward motion of handle 16 has'h'owever movedpivot 19 upward withrespect to lpivot 17-so 'that'line'34 passes abovevpivot 17 and thistoggle `jo`int lhas been released. This permits a `slight movement ofpivot -17 toward `pivot 22 which releases pressure =of vjaw 14 on object30.

It isseen-'that the initial upward motion of handle 16 has released 'themain pressure on Aobject 30 and has brought'stop'27 intoengagement withsaidv handle. Further-upward motion ofhandle 16 therefore carries .link

18 with it, causing-pivot'21 to pass above line 34 also'to release thattogglejoint. The spring 28 then pulls the assembly Aback intotheposition of Figyl where stop 26 limits the opening of thej-jaws'12vand '14 and 4pivot 19 is pulleddown relative to pivots 1`7 and 21whichplaceslink "18 back inside 'handle 1'6.

In'the'conventional locking pliers, a kconsiderableforce is requiredto'fbreaktoggle joint 21 whenthe pliers are In this invention, Y joint21 is not'broken initially, but pressure on said joint is llirstfreducedby breaking a second toggle joint 19 on which handle-16fhas aleverageabout four times asA great asithas -onfjoint 21, pivot 19'^being muchcloser to .pivot 17r than pivot 21. rThis `makes lit very easy to causethe initial movement lof handle 16, and when toggle joint .'21 is'nally'brokem the pressure is `so much reduced that it also openseasily. 'The totalmovement of handle .16 from the closed toftheopenlposition isno greater than in 'fthe vconventional pliers, vbuttheopening force is greatly reduced.

`I claim:

l. In a wrench of the type described, Acomprising a stationary jaw andhandle, arst pivot means supported by @saidfhandle at a distance from`said jaw, and amov- -able jawrvpivotally connected to said handleadjacent said lstationary vjaw and operative with said stationary fjaw,said vmovable'jaw including a second pivot means,

an over-center toggletype jaw closingand releasingmechanism pivotally.connected between said. movablejaw Vand said handle at said rst andsecond ypivot means,.sa.id

rmechanismcompris'ing: a'dual npivot toggle comprisingYzthree:Lpivotally.'connectedflinks, including `aiirst link pivotallyconnected to one of said pivot means, a second link pivotally connectedto said first link at a release toggle joint, over-center stop means forsaid release toggle joint, a third link pivotally connected to the otherof said pivot means and to said second link at a locking toggle joint,over-center stop means for said locking toggle joint, and a movablehandle fixed to one of said links pivoted at said release toggle joint,whereby closing pressure exerted on said movable handle reacts first onsaid release toggle joint to lock said joint in an over-center positionand thence toreact secondly through the then rigid first and secondlinks to the locking toggle joint to move and lock said locking togglejoint in an overcenter position and close said jaws, and openingpressure exerted on said movable handle reacts first on said releasetoggle joint to break the same from an overcenter position and releasesaid jaws.

2. In a wrench of the type described, comprising a stationary jaw andhandle, a first pivot means supported by said handle at a distance fromsaid jaw, said handle including a first pivot means, and a movable jawpivotally connected to said handle adjacent said stationary jaw andoperative with said stationary jaw, said movable jaw including a secondpivot means, an over-center toggle type jaw closing and releasingmechanism pivotally connected between said movable jaw and said handleat said first and second pivot means, said mechanism cornprising: a dualpivot toggle comprising three pivotally connected links, including afirst link pivotally connected to one of said pivot means, a second linkpivotally connected to said first link at a release toggle joint,overcenter stop means for said release toggle joint, a third linkpivotally connected to the other of said pivot means and to said secondlink at a locking toggle joint, overcenter stop means for said lockingtoggle joint, and a movable handle xed to said first link, wherebyclosing pressure exerted on said movable handle reacts first on saidrelease toggle joint to lock said joint in an overcenter position andthence to react secondly through the then rigid first and second linksto the locking toggle joint to move and lock said locking toggle jointin an over-center position and close said jaws, and opening pressureexerted on said movable handle reacts first on said release toggle jointto break the same from an overcenter position and release said jaws.

3. A combination as in claim 2 and with a spring connected to saidrelease toggle in the region of said release toggle joint and to saidstationary handle, to hold said wrench in a normally open position withsaid release toggle joint in an over-center locked position and saidlocking toggle joint in an unlocked position.

4. A combination as in claim 1 and with a second over-center stop meansfor said release toggle joint operative on the release side of deadcenter position of said joint, whereby opening pressure exerted on saidmovable handle reacts first to break said release toggle joint and tolock in an over-center position on said second stop means to reactsecondly through the then rigid first and second links to move and breaksaid locking toggle joint from a locked over-center position to an openposition and release said jaws fully.

5. A combination as in claim 1 and with a second overcenter stop meansfor said locking toggle joint operative on the unlocked side of deadcenter position of said joint, whereby the opening motion of said toggleand the opening of said jaws is limited.

6. A combination as in claim 1 and with the length of at least one ofsaid first and second links between said pivot points thereof less thanthe length of said third link between the pivot points thereof, wherebythe force required to break the release toggle joint to an unlockedposition becomes less than the force required to break the lockingtoggle joint. 7. In a wrench of the type described, comprising pivotally connected stationary and movable jaws, the sta said fixed handle, amovable handle fixed to said first link, said second link being engagedby said movable handle and moved bodily therewith during closingmovement of said movable handle, whereby said first and second links arerigid with one another and locking toggle action occurs at said lockingtoggle joint with said third link functioning as the remaining link ofthe locking toggle, stop means limiting said action of said lockingtoggle when said locking toggle joint has moved to an overcenterposition, said release toggle joint being in an overcenter positionrelative to a line intersecting the pivot axis of the connection betweenthe jaw and first link and the pivot axis of the connection between thethird link and the fixed handle when said locking toggle is in saidovercenter position, said second and third links remaining initiallyrigid relative to one another owing to said overcenter position of saidlocking toggle joint as said movable handle is opened, whereby releasetoggle action occurs at said release toggle joint, with said first linkfunctioning as the remaining link of the release toggle.

8. In a wrench of the type described, comprising pivotally connectedstationary and movable jaws, the st-ationary jaw being provided with ahandle, an over-center toggle type jaw closing and releasing mechanismconnected between the movable jaw and said handle, said mechanismcomprising: a movable handle pivotally connected to said movable jaw ata first pivot point, a first toggle link positioned on the inner side ofsaid movable handle and pivotally connected thereto at a second pointspaced rearwardly along said handle from said first pivot point, saidhandle being engageable with said first toggle link at a point spacedrearwardly from said second pivot point during closing movement of saidmovable handle, a second toggle link pivotally connected at one end tosaid first toggle link at a third pivot point and at its opposite end tosaid fixed handle at a fourth pivot point, said movable handle and saidfirst toggle link when in engagement during said closing movementforming one arm of a locking over-center toggle, and said second linkconnected thereto at said third pivot point forming the other arm ofsaid locking over-center toggle, stop means on said second linkengageable with said first link to arrest said closing movement of saidmovable handle when said locking toggle has reached a predeterminedover-center position, said second pivot point being substantially inalinement with said first and fourth pivot points when said lockingtoggle is in said over-center position, the portion of said movablehandle between said first and second pivot points constituting one armof a release toggle, and said first and second links constituting theother arm of said release toggle, with the toggle joint thereof at saidsecond pivot point, said first andsecond links forming an initiallyrigid toggle arm during opening movement of said movable handle owing tosaid overcenter position of said locking toggle, whereby release toggleaction occurs at said second pivot point.

References Cited in the le of this patent UNITED STATES PATENTS2,443,153 Wells June 8, 1948 2,574,676 Waterbury Nov. 13, 1951 2,589,511Redman Mar. 18, 1952 2,590,750 Burns Mar. 25, 1952 2,604,803 McCann July29, 1952 2,669,145 Mead Feb. 16, 1954 2,685,218 Burns Aug. 3, 1954

